This application is related to magnetic induction heating of gear teeth and components, and in particular to an apparatus and method for moving magnets relative to gear teeth to effectuate magnetic inductive heating.
Case hardening of a work-piece through heat treatment has been a common practice in the bearing and gear industry for many years. Various means and methods have been known and utilized to various degrees over the years.
Induction heating is well known and utilized throughout the industry for its effectiveness and environmental friendliness. As an electrically conductive work-piece is brought into a varying magnetic field, eddy currents are generated. These eddy currents result in an Ohm loss that is manifested as heat generation. Traditionally, the varying magnetic field is generated by a copper tooling coil which is energized with an alternating electric current, the frequency of which is regulated by power electronic switches such as IGBTs and MOSFETs. The tooling coil in most cases is placed stationary relative to the work-piece, and the work-piece is moved relative to the coil. Heat generation and the heated volume in the work-piece are determined by (1) magnetic flux density, (2) electric conductivity of the work-piece, and (3) the frequency of magnetic field variation. To increase heat generation, electric voltage and frequency of the tooling coil has to be increased. This results in a noticeable power loss within the tooling coil and power electronic switches. In addition, the tooling coil is not very flexible and the system cost is relatively high.